J. Planar Chromatogr. 30, 375-385 (2017). HPTLC of synthetic peptides on silica gel and RP-18 with water and methanol with the addition of proper ion-pairing reagent to study the influence of metallic impurities on the retention and efficiency of separation of peptides. Detection by dipping into 2 % ninhydrin solution in acetone ‒ methanol ‒ glacial acetic acid 25:25:2. The contents of trace elements in areas scraped off from the chromatographic plates were determined by flame technique of atomic absorption spectrometry. The impurities present in the adsorbents may cause characteristic disruption of solute zone shape and overall distortion of the chromatogram during the development.

J. Planar Chromatogr. 30, 481-487 (2017). HPTLC of pantoprazole sodium sesquihydrate (1), metronidazole (2) and clarithromycin (3) on silica gel with ethyl acetate and absolute ethanol (3:1) ‒ heptane ‒ 33 % ammonia 14:5:1. Quantitative determination by absorbance measurement at 280 nm. The hRF values for (1) to (3) were 49, 72 and 83, respectively. Linearity was between 0.8 and 8 μg/zone for (1), 4 and 40 μg/zone for (2) and 5 and 50 μg/zone for (3). LOD and LOQ were 153 and 462 ng/zone for (1), 760 and 2310 ng/zone for (2) and 880 and 2670 ng/zone for (3), respectively. The intermediate/interday/intra-day precision was below 2 % (n=3). Average recovery was 99.6 % for (1), 99.8 % for (2) and 100.1 % for (3).

J. Planar Chromatogr. 31, 105-111 (2018). HPTLC of 13 quinobenzothiazine derivatives on RP-18 with acetone as organic modifier and aqueous TRIS buffer with pH 7.4 and ionic strength of 0.2 M. The contents of the organic modifier in the mobile phase ranged from 40 to 80% in 5 % increments. Lipophilicity parameters were determined for the analysis of structure–activity relationship (QSAR).

J. Planar Chromatogr. 31, 202-206 (2018). HPTLC of vulgarin (1) and epivulgarin (2) in the aerial parts of Artemisia judaica on silica gel with petroleum ether – acetone 7:3. Quantitative determination by absorbance measurement at 224 nm. The hRf values for (1) and (2) were 30 and 36, respectively. Linearity was in the range of 100-700 ng/zone for (1) and (2). The intermediate precision was below 1.5 % (n=6). The LOD and LOQ were 13 and 44 ng/zone for (1) and 14 and 47 ng/zone for (2), respectively. Recovery was between 97.1 and 99.6 % for (1) and 97.6 and 99.0 % for (2).

Food Control 90, 249-258 (2018). HPTLC of tyramine in the bacterial strains isolated from kung-som on silica gel with chloroform – diethylester – triethylamine 3:2:1. Detection by spraying with isopropanol – tri-ethanolamine 4:1. The fluorescent dansyl derivative was visualized under UV light.

J. Planar Chromatogr. 31, 235-242 (2018). HPTLC of lormetazepam on silica gel with acetonitrile – water 3:2. Quantitative determination by absorbance measurement at 241 nm. The hRf value for lormetazepam was 44. Linearity was in the range of 1.0-7.5 μg/zone. The intermediate precision was below 4 % (n=3). The LOD and LOQ were 0.26 and 0.77 μg, respectively. Average recovery was 100.9 %. Comparable results were obtained with a validated HPLC method.

J. Liq. Chromatogr. Relat. Technol. 41, 595-603 (2018). Review on different applications of planar chromatography for the analysis of essential and non-essential amino acids and their derivatives, including the use of ninhydrin and other spray reagents for the detection of amino acids by TLC and the formation of color using 6-pyridin-2-yl-5,6-dihydro-benzo[4,5]imidazo [1,2-c] quinazoline and chloranil.

Phytochemistry 155, 37-44 (2018). HPTLC of pine resins collected from Abies grandis, Pseudotsuga menziesii, Picea abies, Pinus sylvestris L. and Pinus strobus L. in a forest area of The Netherlands during early and late spring on silica gel with toluene – isopropyl alcohol – diethyl ether 16:1:3. Detection by spraying with 2 mL of anisaldehyde sulfuric acid solution, followed by heating at 100 ºC for 3 min. Qualitative identification under UV light at 366 nm. Most of the metabolites detected in GC-MS were confirmed by HPTLC analysis. HPTLC proved to be an important technique for metabolic profiling.